黑米中矿质元素铁、锌、锰、磷含量的遗传效应研究

采用禾谷类作物种子胚乳数量性状模型,分析黑米稻品种双列杂交Ｆ１和Ｆ２种子的Ｆｅ、Ｚｎ、Ｍｎ、Ｐ含量的遗传效应。结果表明,４种矿质元素含量同时受制于种子直接遗传效应、母体效应和细胞质作用影响。其中,Ｆｅ、Ｚｎ、Ｍｎ含量的种子直接效应比母体效应和细胞质效应的作用更大;Ｐ含量则主要受种子直接加性、母体加性和显性效应共同作用。Ｆｅ、Ｚｎ、Ｍｎ含量的种子直接遗传率较高,在杂种早代分别结合农艺性状选择单株上各     

稻米营养品质种子效应和母体效应的遗传分析

采用谷类作物种子数量性状的遗传模型,以珍汕９７Ａ等６个籼型不育系与测早２－２等,３个早籼恢复系进行不完全双列杂交,对籼型杂交稻稻米营养品质性状进行了遗传分析。结果表明：稻米蛋白质含量和蛋白质指数主要受制于母体遗传效应,但亦受到种子基因效应的影响;赖氨酸含量和赖氨酸指数则主要与种子基因效应有关,其中赖氨酸含量还受到母体加性效应的影响。除赖氨酸指数外,其它营养品质性状的种子直接遗传率和母体遗传率均已达到极显著水平。遗传效应预测值表明,选用浙南１号Ａ和２６７１５较易获得稻米营养品质较为理想的籼型杂交稻组合。     

籼型黑米粒形性状的遗传效应及其与矿质元素含量的遗传相关性

采用禾谷类作物种子数量性状的遗传模型,分析了灿型黑米稻品种双列杂交F1和F2种子的粒重,粒长,粒宽和粒长／粒宽等粒形性状的遗传效应及其与米粒中矿质元素Fe,Zn,Mn和P含量的遗传相关性,结果表明：4种粒形性状同时受制于种子直接遗传效应,母体效应和细胞质作用影响,其中种子直接遗传效应比母体效应和细胞质效应的作用更大,且种子直接遗传效应以加性效应占主导,粒重,粒宽和粒长／粒宽的种子直接遗传率较高,杂种早代单粒选择效果较好,粒长的种子直接遗传率和母体遗传率均属中等,较高世代的杂种进行单株选择和单粒选择均有一定效果,4种粒形性状与其米粒中矿质元素Fe,Zn,Mn和P含量表现较强的种子直接加性相关,直接显性相关,细胞质相关,母体加性相关和母体显性相关,在特种稻育种实践中,可以通过粒形性的间接选择,达到改良其矿质元素含量等营养品质性状的目标。     

Detecting relationships between amylose content and amino acid contents of <Emphasis Type="Italic">indica</Emphasis> rice with conditional approach

The relationship between the genetic effects of endosperm, cytoplasm and maternal plant on amylose content (AC) and amino acid contents of indica rice was studied using unconditional and conditional analysis methods. The results indicated that the protein content (PC) and brown rice weight (WBR) could significantly affect the relationships between AC and amino acid contents of rice. The phenotypic and genotypic covariances between AC and amino acid contents were most significantly negative under the interference of PC or WBR, but most of the relationships for the paired traits were not significant after excluding the influence of PC or WBR on AC. For the conditional genetic relationship analysis of different genetic systems including endosperm, cytoplasm and maternal plant, visible changes were found in many genetic correlation components between AC and amino acid content after eliminating the influences of PC, especially, for the endosperm or maternal additive effects, endosperm additive or dominance interaction effects and maternal additive interaction effects. The relationships of the paired traits conditioned on WBR were mainly controlled by the endosperm dominance or additive interaction effects.     

Genetic analysis of salt tolerance during germination in Lycopersicon

Summary The salt-tolerant cultivated tomato (Lycopersicon esculentum) accession, PI174263, and a sensitive cv, UCT5, were crossed to develop reciprocal F₁, F₂ and BC₁ populations for genetic analysis of salt tolerance in tomatoes during seed germination. Variation was partitioned into embryo, endosperm and maternal (testa and cytoplasmic) components. Generation means analysis indicated that there were no significant embryo (additive, dominance or epistatic) effects on germination performance under salt stress. Highly significant endosperm additive and testa dominance effects were detected. The proportion of the total variance explained by the model containing these two components was R²=98.2%. Variance component analysis indicated a large genetic variance with additive gene action as the predominant component. Furhter inspection indicated that this variance was attributable to endosperm additive effects on germinability under salt stress. Narrow-sense heritability was estimated as moderately high. Implications for breeding procedures are discussed.     

Genetic and genotype × environment interaction effects for the content of seven essential amino acids in<Emphasis Type="Italic">Indica</Emphasis> rice

It is necessary for rice breeders to understand the genetic basis of nutrient quality traits of rice. Essential amino acids are most important in determining the nutrient quality of rice grain and can affect the health of people who depend on rice as a staple food. In view of the paucity of genetic information available on essential amino acids inindica rice, we estimated the genetic main effects and genotype × environment (G × E) interaction effects on the content of essential amino acids. Nine cytoplasmic male sterile lines as females and five restorer lines as males were introduced in a North Carolina II design across environments. Estimates of the content of the essential amino acids valine, methionine, leucine and phenylalanine showed that they were mainly controlled by genetic main effects, while the contents of threonine, cysteine and isoleucine were mainly affected by G × E effects. In the case of genetic main effects, both cytoplasmic and maternal genetic effects were predominant for all essential amino acids, indicating that selection for improving essential amino acid content based on maternal performance would be more effective than that based on seeds. The total narrow-sense heritabilities were high and ranged from 0.72 to 0.83. Since general heritabilities for these essential amino acids (except for cysteine) were found to be much larger than G × E interaction heritability, the improvement of content of most essential amino acids under selection would be expected under various environments. Rice varieties such as Zhenan 3, Yinchao 1, T49, 26715, 102 and 1391 should be selected as optimal parents for increasing the content of most essential amino acids, while the total genetic effects from Zhexie 2, Xieqingzao, Gangchao 1, V20, Zuo 5 and Zhenshan 97 were mainly negative and these parents could decrease the contents of most essential amino acids.     

Genetics and caging type affect birth weight in captive pigtailed macaques (Macaca nemestrina)

The heritability of birth weight was estimated in 3,562 captive pigtailed macaques using 30 years of breeding and pedigree records. Based on a pedigree of over 12,000 animals, quantitative genetic analyses were performed using statistical variance decomposition methods. The model included additive genetic effects, cytoplasmic genetic effects, birth environment, shared maternal environment, and unmeasured environmental effects. The results demonstrated a strong (h(2) = 0.51) heritable component of birth weight overall, and included significant additive genetic heritability (h(2) = 0.23), and cytoplasmic heritability (h(2) = 0.09). In addition, a significant effect of birth location and cage type was identified, explaining an additional 6% of birth weight variance. The use of a nonhuman primate model for studying the effects of genes on birth weight eliminated many of the problems associated with confounding variables in human studies, and allowed for the quantification of a heritable component of birth weight.     

小麦蛋白质组分含量的配合力和遗传力分析

利用5个小麦亲本,按Griffing方法4组配一套完全双列杂交,研究小麦籽粒蛋白质组分的配合力和遗传力。结果表明,同一性状不同亲本的一般配合力效应和不同组合间的特殊配合力效应差异都较大。球蛋白、醇溶蛋白和谷蛋白含量的遗传主要受加性基因控制,清蛋白含量的遗传不存在加性基因作用,以显性基因作用为主。 Abstract：　A set of diallel crosses involving 5 wheat parents, according to the random model of Griffing Method 4, was made to study the combining ability and heritability of grain protein components in wheat. The results indicated that GCA effects of different parents for the same trait varied significantly. And SCA effects of different combination studied varied obviously. The inheritance of globulin, gliadin and glutenin contents were mainly controlled by additive genes. Dominant genes functioned mainly on albumin content without additive gene.     

Genetic basis of seed setting in alfalfa

Summary The genetic basis of seed setting was evaluated in seven clones of alfalfa selected under predominantly self-pollinating conditions. They were hand crossed in all possible combinations. Their compatibility was studied by the percentage of flowers forming pods and number of seeds per pod during crossing. The variances for GCA, SCA and reciprocal effects were significant for percentage of pod set with a narrow sense héritability of 64 %. This suggested maternal influence of clones on percent pod set, controlled primarily by additive genetic components. GCA was the only significant component for number of seeds per pod with a narrow sense heritability of 71%. There were wide differences between the clones in their relative magnitude of GCA, SCA and reciprocal effects for both traits used as compatibility indexes. Performance of the diallel crosses was judged by studying seed yield and its related characters, namely seeds per pod, dry matter per plant, frost resistance, plant vigor and plant height. Although GCA and SCA variances were significant for all characters, reciprocal differences in general were absent. The SCA values were very high as compared to GCA. Narrow sense heritability values were very low while broad sense heritability were much higher. This suggested that almost none of the variation was due to additive genetic components and all the variability is controlled by interactions of a digenic, trigenic and quadrigenic nature and heterzozygosity. Heterosis was evaluated by comparing the seed yield of single crosses with their mid-parent and high-parent, and very high values were observed. Thus selection of better genes may not be feasible and further improvement in selected clones may have to be brought about by utilization of various interactions and heterosis. An attempt was made to find combinations of characters that may be used for the selection of seed yield but none were found to be satisfactory.     

The dynamic gene expression from different genetic systems for protein and lysine contents of indica rice

The dynamic expression of genes for protein and lysine contents of rice grain under different environments was carried out with time-dependent measures by using the developmental genetic models for quantitative traits of triploid endosperm in cereal crops. The results showed that the genetic effects, especially genotype × environment (GE) interaction effects from the genes expression of different genetic systems including triploid endosperm, cytoplasm and diploid maternal plant were important for the performance of both nutrient quality traits at all developmental times/stages of rice grain. The conditional genetic variance analysis found that the activation of quantitative genes especially from endosperm and maternal plant genetic systems for protein and lysine contents was gradually carried through the developmental process of rice grain. The net genetic effects showed that the new expression of quantitative genes for protein and lysine contents was more active at late filling stage (15–21 days after flowering) and maturity stage (22–28 days) of rice grain. Also the sequential expression of cytoplasmic genes cannot be ignorable for the development of nutrient quality traits. The phenomena that some genes could continuously express for several developmental stages or the genes expression could be interrupted among developmental stages of rice grain was detected especially for net endosperm additive main effects or maternal additive main effects. The differences of genetic relationships from different genetic systems were found for protein and lysine contents among developmental times of rice grain.     

On the possible origin and evolution of the genetic code

The genetic code is examined for indications of possible preceding codes that existed during early evolution. Eight of the 20 amino acids are coded by ‘quartets’ of codons with four-fold degeneracy, and 16 such quartets can exist, so that an earlier code could have provided for 15 or 16 amino acids, rather than 20. If two-fold degeneracy is postulated for the first position of the codon, there could have been 10 amino acids in the code. It is speculated that these may have been phenylalanine, valine, proline, alanine, histidine, glutamine, glutamic acid, aspartic acid, cysteine and glycine. There is a notable deficiency of arginine in proteins, despite the fact that it has six codons. Simultaneously, there is more lysine in proteins than would be expected from its two codons, if the four bases in mRNA are equiprobable and are arranged randomly. It is speculated that arginine is an ‘intruder’ into the genetic code, and that it may have displaced another amino acid such as ornithine, or may even have displaced lysine from some of its previous codon assignments. As a result, natural selection has favored lysine against the fact that it has only two codons. The introduction of tRNA into protein synthesis may have been a cataclysmic and comparatively sudden event, since duplication of tRNA takes place readily, and point mutations could rapidly differentiate members of the family of duplicates from each. Two tRNAs for different amino acids may have a common ancestor that existed more recently than the separation of the prokaryotes and eukaryotes. This is shown by homology of twoE. coli tRNAs for glycine and valine, and two yeast tRNAs for arginine and lysine.     

Genetic studies of anther culture ability in rice (Oryza sativa)

Inheritance of three anther and culture characters, callus induction, green plant regeneration and culture efficiency was studied using incomplete diallel crosses with a gamete model. It was suggested that callus induction was mainly controlled by gametic additive effects and with less effect of the maternal effects. Green plant regeneration was mainly determined by maternal effects with less influence of gametic additive effects. Culture efficiency was controlled by gametic additive, maternal and cytoplasmic effects. Cultivar Lunhui 422 showed positive genetic effects for all three traits and was a very good parent for rice anther culture breeding. Significant positive heterosis was observed for callus induction. Both gametic additive and maternal correlations contributed to the significant genotypic and phenotypic correlations between callus induction and green plant regeneration suggesting these two traits to be linked.Abbreviations 2,4-d 2,4-dichlorphenoxyacetic acid - NAA -napthaleneacetic acid     

稻米营养品质性状的间接选择和遗传改良

利用9个籼型不育系与5个籼型恢复系按不完全双列杂交方式配制杂交组合,采用胚乳遗传模型分析籼稻碾磨和外观品质与营养品质性状间的多种遗传相关．结果表明,籼稻稻米营养品质与其它一些品质性状间存在着较强的胚乳直接加性相关、胚乳直接显性相关、细胞质相关、母体加性相关和母体显性相关．糙米重与赖氨酸指数等以正向加性相关和细胞质相关为主的成对性状,具有较好的间接选择效果．除了糙米宽与营养品质成对性状外,糙米长厚比与蛋白质含量等以负向加性相关为主、细胞质相关不明显或为负值的成对性状,将不易取得良好的同步改良效果．多数细胞质相关具有正向的较大相关系数,表明控制不同稻米品质性状表达的细胞质效应之间的相关是不可忽视的．糙米宽与蛋白质含量等以显性相关为主的成对性状则可以在杂交稻育种中加以应用．     

Inheritance of leaf geranylflavanone production and seed production within and among chemically distinct populations of Mimulus aurantiacus

Most models to account for variation in defensive chemical production in plants assume that defensive chemical production is a quantitative trait determined by the additive effects of many genes, and that defensive chemical production is genetically negatively correlated with fitness. The inheritance of quantities of geranylflavanones and seed production, an estimate of female fitness, was studied in reciprocal crosses between several chemically distinct populations of Mimulus aurantiacus to test those assumptions. Genetic analyses using reciprocal crosses were used to test for maternal or paternal genetic effects. The quantities of individual geranylflavanones of the hybrids generally were inherited with dominance or over-dominance. Reciprocal genetic effects were rarely found. Within populations, leaf resin production in M. aurantiacus was independent of seed production. Results are consistent with previous reports suggesting that any evolutionary change in geranylflavanone production within populations may be constrained by low levels of genetic variation in geranylflavanone production.     

Generation means analysis for productivity in two diverse peanut crosses

Summary Utilization of exotic germplasm resources for population improvement in peanut (Arachis hypogaea L.) has increased as the need to increase genetic diversity among peanut cultivars was recognized. Progeny of crosses of two unadapted germplasm lines (GP-NC 343 and FESR-11-P11-32) with an adapted cultivar (NCV11) of peanut were evaluated for the genetic factors influencing the inheritance of yield and fruit characters in crosses among diverse lines. Objectives were to (1) estimate the relative importance of additive and nonadditive genetic effects in the inheritance of yield and fruit characters in two diverse peanut crosses; (2) determine the proportion of exotic germplasm that gave the optimum combination of mean productivity and genetic variability for each of the crosses; (3) relate the results to theories regarding the transfer of desirable alleles from exotic germplasm into adapted breeding populations. Crosses and backcrosses were made to generate germplasm lines (ten generations) ranging from 0 to 100% exotic germplasm for each cross. The populations were evaluated in replicated field trials. Yield and six fruit characters were measured, and a weighted analysis of variance was conducted to determine if significant differences existed among generations. Generation means analyses were performed for each trait measured in each of the crosses using both three- and six-parameter models, which were tested for goodness-of-fit with a joint-scaling test. Significant differences were detected among generations for most traits measured in both crosses. Estimates of additive genetic effects were significant for pod weight and seed weight in cross 1 (NC-V11 x GP-NC 343) and for all traits in cross 2 (NC-V11 x FESR-11-P11-32) except seedpod ratio. Significant estimates of dominance effects were found for pod length, pod width, and pod weight in cross 1 and for pod length in cross 2. No significant estimates of digenic effects were observed in cross 1, whereas in cross 2 estimates of additive x dominance epistatic effects were significant for yield and pod length, while estimates of additive x additive effects were significant for seed number. Regression of trait means on generations showed a curvilinear response for all traits in cross 1 except seed weight, which gave a linear response. For all traits in cross 2, the relationship between productivity and proportion of unadapted germplasm was effectively linear. Based on generation means and variances, progeny from the first or second backcross generation to the recurrent parent should be expected to give an optimum combination of mean productivity and relative variability in the population.The research reported in this publication was funded in part by the North Carolina Agricultural Research Service     

籼粳交稻米蒸煮品质性状的遗传效应分析

以2个粳型光温敏核不育系和4个籼稻品种为材料,配制籼粳交组合,用包括基因型×环境互作效应的胚乳性状遗传模型对3个蒸煮品质性状(直链淀粉含量、胶稠度、碱消值)进行了遗传研究,结果表明:直接加性和母体加性效应对三个性状的遗传变异起主要作用.基因型×环境互作主要表现为显性×环境以及细胞质×环境互作.直链淀粉含量的普通遗传率都不显著,只有较高的互作母体遗传率;胶稠度具有显著的普通直接遗传率和互作细胞质遗传率;碱消值的普通直接遗传率和普通母体遗传率都极显著.根据遗传效应预测值对供试亲本的利用价值作了评价。     

Genetics of tassel branch number in maize and its implications for a selection program for small tassel size

Summary Tassel branch numbers of six crosses of maize (Zea mays L.) were analyzed to determine inheritance of this trait. Generation mean analyses were used to estimate genetic effects, and additive and nonadditive components of variance were calculated and evaluated for bias due to linkage. Both narrow-sense and broad-sense heritabilities were estimated. Additive genetic variance estimates were significant in five of the six crosses, whereas estimates of variance due to nonadditive components were significant in only three crosses. Additionally, estimates of additive variance components usually were larger than corresponding nonadditive components. There was no evidence for linkage bias in these estimates. Estimates of additive genetic effects were significant in four of six crosses, but significant dominance, additive × additive and additive × dominance effects also were detected. Additive, dominance, and epistatic gene action, therefore, all influenced the inheritance of tassel branch number, but additive gene action was most important. Both narrow-sense and broadsense heritability estimates were larger than those reported for other physiological traits of maize and corroborated conclusions concerning the importance of additive gene action inferred from analyses of genetic effects and variances. We concluded that selection for smalltasseled inbreds could be accomplished most easily through a mass-selection and/or pedigree-selection system. Production of a small-tasseled hybrid would require crossing of two small-tasseled inbreds. We proposed two genetic models to explain unexpected results obtained for two crosses. One model involved five interacting loci and the other employed two loci displaying only additive and additive × additive gene action.Journal Paper No. J-9231 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa 50011. Project No. 2152     

VARIATION IN SEED CHARACTERS IN NEMOPHILA MENZIESII: EVIDENCE OF A GENETIC BASIS FOR MATERNAL EFFECT

A growing body of evidence indicates that phenotypic selection on juvenile traits of both plants and animals may be considerable. Because juvenile traits are typically subject to maternal effects and often have low heritabilities, adaptive responses to natural selection on these traits may seem unlikely. To determine the potential for evolutionary response to selection on juvenile traits of Nemophila menziesii (Hydrophyllaceae), we conducted two quantitative genetic studies. A reciprocal factorial cross, involving 16 parents and 1960 progeny, demonstrated a significant maternal component of variance in seed mass and additive genetic component of variance in germination time. This experiment also suggested that interaction between parents, though small, provides highly significant contributions to the variance of both traits. Such a parental interaction could arise by diverse mechanisms, including dependence of nuclear gene expression on cytoplasmic genotype, but the design of this experiment could not distinguish this from other possible causes, such as effects on progeny phenotype of interaction between the environmental conditions of both parents. The second experiment, spanning three generations with over 11,000 observations, was designed for investigation of the additive genetic variance in maternal effect, assessment of paternal effects, as well as further partitioning of the parental interaction identified in the reciprocal factorial experiment. It yielded no consistent evidence of paternal effects on seed mass, nor of parental interactions. Our inference of such interaction effects from the first experiment was evidently an artifact of failing to account for the substantial variance among fruits within crosses. The maternal effect was found to have a large additive genetic component, accounting for at least 20% of the variation in individual seed mass. This result suggests that there is appreciable potential for response to selection on seed mass through evolution of the maternal effect. We discuss aspects that may nevertheless limit response to individual selection on seed mass, including trade-offs between the size of individual seeds and germination time and between the number of seeds a maternal plant can mature and their mean size.     

Maternal effects and generation mean analysis of seed-oil content in cotton (Gossypium hirsutum L.)

Summary The nature of gene action and of maternal influence governing cottonseed oil attributes were determined with four lines, two each with high and low seed-oil percentage. For this purpose, P1, P2, F0, F1, F2 and alternative sets of BC1 and BC2 generations were analysed in six cross-combinations and their reciprocals. Marginal extents of heterosis for seed-oil percentage were noticeable in F1, with inbreeding depression in F2. Data from reciprocal backcrosses provided evidence in favour of maternal rather than cytoplasmic effects of seed-oil development. Relatively higher extents of heterosis, sizeable inbreeding depression and reciprocally unequal F2 averages were characteristic of the seed index trait, which often showed a reversal of effects from F1 to F2. Reverse reciprocal backcrosses exhibited some differences, including greater resemblance between the types, (A/B)A and (B/A)A, in addition to variable dose effects in seed index. Thus, the differences between F1 seed index values were not due to cytoplasmic influence. Positive heterotic effects for seed-oil index, especially among the backcrosses, ranged between 16.08% and 47.29% over midparent averages. Genetic component estimates from analysis of similar sets of crosses differing only in reciprocal backcrosses, and also from sets of reciprocal crosses between any two parental combinations, were inconsistent. Scaling tests detected presence of epistasis within and between a majority of cross-combinations. Despite reciprocal differences, additive gene effects for seed-oil percentage were significant in 7 out of 24 crosses, representing high x low, low x high and low x low seed-oil parents. Those were, however, accompanied by significant dominance effects of higher order. In crosses involving low seed-oil percentage parents SA1060 and SA229, all six components were detected significant, with opposite effects of dominance and dominance x dominance epistatic components. Significant additive components were also detected for seed index and seed-oil index in 7 and 5 out of 24 crosses, respectively. In the inheritance of seed index and seed-oil index, dominance effects were more important. Epistatic components of additive x additive, and to a lesser extent, those of dominant x dominant were found significant.